Esters of acylated hydroxycarboxylic acids



Patented Sept. 9, 1952 ESTERS or ACYLATED HYDROXY BOXYLIC ACIDS cam Charles H. Fisher, New Orleans La., and Martin L. Fein, Riverside, N=.'J., assignors to the United States of Americaas re tary of Agriculture presented by the Secre- No Drawing: Application March 27, 1950, Serial N 0.' 152,269

11 claims. (p1. 259 4109) H (Granted underythe act of ,March 3, 1883, as

amended April 30, 1928;. 370 0. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the inventionherein described, if patented in any country, may be manufactured and used by or for the Government of the United States of America, for governmental purposes throughout the world, without the payment to us of any royalty thereon.

This application is a continuation in part of our copending application Serial No. 663,337 filed April 19, 1946, now PatentNo. 2,518,456.

This invention relates to new compositions of matter and the methods of making the same, and, in particular, to compositions comprising an ester of acylated lactylla'ctic acid corresponding to thegeneral formula:

We have found that such an ester is formed in admixture with the corresponding ester of acylated lactic acid having the general formula: 25

having properties which renderjthem pseiul as plasticizersand modifying agents for plastic compositions and other similarproducts. The esters" of this invention are formed on heating at reaction temperature, a higher aliphatic, saturated monocarboxylic acid, that is an acid containing more than 5 carbon atoms,

the equimolecular amount, of an alkyl lactate,

and removing the water formed in the reaction by distillation during the reaction. I

The alkyl lactates best adapted for use in our monocarboxylic acid include 4 flalsladistilmte.

process are those containing from 2 to 12carbon atoms in the alkyl group, such as ethyl, propyl,

butyl, amyl, hexyLheptyl, octyl, 2-ethyl-hexyl, nonyl or lauryl lactates.

for example those containing from 6 to 18 carbon atoms, such as caproic, heptoic, caprylic, rnyristic, lauric or stearic acids. of the resulting products the process is most advantageously applied to the use of butyl lactate in conjunction with lauric acid.

The reaction rate can be increased by conducting the'process in the presenceof a catalyst such-as sulfuric acid, toluene sulfonic acid or other acidic esterification catalysts, and removal of water during the reaction is facilitated by the u use of an'entraining a toluene or the like. Formation of 'the desired products can be promoted by addition tothe reaction mixture of suitable amounts of the corresponding alkyl ester of the carboxylic acid used as the reactant, or of thisester and also of the corresponding alkyl ester of lactyllactic acid.

Thefollowing examples illustrate the invent EXAMPLE:

ted v'vitha modified Barrett moisture trap and condenser, as well as a side arm'to hold a thermometer during the esterification and a capillary 5 bubbler during distillation of the products. Nine ml. water was collected in the trap in 3 hours.

On cooling the catalyst was neutralized byadding a slight excess of calcium lactate. The

reaction mixture was then fractionated under vacuum and the following products were isolated I n-Butyl lactate B. R. 30-40/1 mm.; 50 grams {0.25 mole) n-Butyl' lactyllactate B. R. 72-76 1 28.3 grams (0.13 mole) n-Butyl laurate B. R. 112/ .3-

.4.mm.; 145.9 grams with an excess, and preferablywith at least twice (05711111016) neBut yl lactate laurate B. R. 146- grains (0.22 mole) Suitable aliphatic In view of the superior properties gent such as benzene,-

ion.

The results thus 146-152 c. for 4 hours after which 0.2 mole caprylic acid, 0.5 mole of capryl lactate and 0.27

Table 1 II III IV V VI. VII. VIII IX; X.

Reactants:

Laurie Acid, moles l 1 0.5 0.6 0.5 0.5 0.5 0.5 0.5 n-Butyl Lactate, moles" 3 3 1 1 l 1 I I. 1 n-Butyl Laurate, mo1es 0.5. .i... 0,,5. p-Toluene Sulfonic acid,

gm. (monohydrate) 0.1 l l l l. I 4 l Entrainer:

Benzene, ml 1.- .l.. v 100.. .100

m1 "a; a a as m a, r l D 184 j .-1 1 8,; Reach Temperature 196 196 153. c 239 120 rss .142 1157 Reaction Time, hrs 13 ll 10 2 2 5 5' 1 3;. Recovered Products: 1

n-Butyl laurate, mo1es-.. 0.5 0.5 0.1 0.2 0.3 0.2 0.6 0.3 0.6. n-Butyl lactyl lactate, 1

moles 0.4 0.4 0.1 0.1 0.1 0.1 I 0:1v 0.1 10.1. n-Butyl lactate laurate,

moles. 0.3 0.4 0.2 0.2 0. 2. 0.2 0. 3. V 0.1 0.2

Our preferred product, butyl lactyllactate:

laurate, is not listed among the recovered products described above, in Example I, because it is inthedistillation residue remaining after distillation removal of the butyl laurate fraction;

This is fully described inExample. XV bel0w;. particularly in the paragraphs preceding and followingTable 2. The butyl laurate and butyl;

lactyllactate fractions v obtained on distillation. arepreferably returned to the reaction in order to. increase the yields of the said preferred prod..- uct. This is also. explained in ExampleiXV.

EXAMPLE XI Onemoleof n-butyl, lactate-was reacted with 0.5. mole of lauric acid as described in Example,

I, using 0.25 gram of concentrated sulfuric acid as a catalyst and 100 ml. of toluene as the en-. training agent. The reaction mixture was heated atabout 148 0., for approximately 9. hours.

Vacuum distillation'of the products so obtained. yielded 0.1 mole of n-butyl lactyl lactate, 0.2 mole.

of n-butyl lactate laurate and. 0.2 mole of n-butyl laurate.

EXAMPLE XII 0.1 mole of sec. butyl lactyl laurate, 0.1mole of sec. butyl laurate and 0.3 mole of sec. butyl lactate laurate.

- EXAMPLE XIII One moleofcapryl lactate was reacted with 0.5 mole of n-caprylic acid, as described in Example I, using 1 gram of p-toluene sulfonic acid as a catalyst and ml. of toluene as; the entrain,- ingagent. The reaction mixture was heated. at

mole capryllactate'n-caprylate were recovered by vacuum distillation.

EXAMPLE XIV The procedure described in Example I was. used in reacting 1 mole of capryl lactate with-0.5 mole lauric acid, at 152-153- C. for; 3.5. hours, in the. presence of. 1 gram p-toluene sulfonic acid monohydrate, and using 100 ml. toluene as'the. entraining agent. Vacuum distillation of the prod,- uct gave 0.37 mole capryl lactate laurate.

EXIAMPLE XV" The distillates colleetedat temperatures above the boiling range ofthe n-butyl lactate laurate fraction, on vacuum distillation of the reaction products in each of the Examples: I through X,

were combined and the resulting mixture dis tilled in vacuum. The fraction collected at. l86- 190 C./ 1.2 mm. was found to consist essentially of butyl lactyl lactate laurate having the following characteristics.

Ester equivalent, 132.6

C: Found, 65.47%

Calculated, 65.97

I-I: Found, 10.02%

Calculated, 10.07%

A series of experiments was conducted according to the general procedure described in Example I. In each of 'theseexperiments lmole oi butyl lactate and" 0.5v mole of lauric acid were used, and theweight ratios; of catalyst" and entraining agent to the total amount of other ingredients were maintained constant- The butyl laurate and butyl lactyllactate:fractions obtainedv on distillation of the reaction product of each experiment were addedto thereactants' of the succeeding run. The experimental. data so obtained are listed in Tabler2.

Table 2 Example: XVI XVIII XVIII. XIX XX, XXI

Composition of Reaction Mixture;

n-Butyl Lactate, grams 148 a 146- 146 146 146 146 Laurie Acid, grams; 100 100 I 100 100 100 I00;

n-Butyl-Laurate, grams 76 13,9 17,0 222 252, n-Butyl Lactyllactate, grams 28 40' 58- 62 p-Toluene sulfomc acid, grams. 1' 1:4 1.] l. 9 2. 15 2.22

Toluene; ml.-.-.' 100 I40 170, 199, 215,, 22 Products Recoveredi n-Butyl Lactate, grams. 46 55. 6.6 53. 78' 61' n-Butyl Laurate, grams 76 139 170 f 222 252 255:

n-Butyl Lactyllactate, grams. 28 t 40 58- 62 49- 63 Distlllatlon Residue 78' 96 I 104 115 138 In all these experiments the product obtained as the distillation residue following removal of the butyl laurate fraction had a substantially constant index of refraction n4 1.4403i0.0005, and on redistillation was found to consist essentially of butyl lactate laurate and butyl lactyllactate laurate in the molecular proportions of approximately 2 to 1.

Thus it was found that within certain limits an equilibrium of products and reactants is reached, and that best yields of the desired products that is, butyl lactate laurate and butyl lactyllactate laurate are obtained on using an initial mixture containing approximately 1 mole of butyl laurate, and 0.3 mole of butyllactyllactate, per 1 mole of butyl lactate and 0.5 mole lauric acid.

Similar results are obtained on using other alkyl esters in place of the butyl esters of the foregoing examples, and other higher fatty acids containing from 6 to 18 carbon atoms in lieu of lauric acid.

The plasticizing efficiency of some of the prodnets of this invention as compared with di-2- ethyl hexyl phthalate, was determined by compounding them with polyvinyl chloride-acetate copolymer (95% vinyl chloride, 5% vinyl acetate) using a procedure analogous to that described by Kent and Weaver, 1947 India Rubber World, 115,

Having thus disclosed our invention we claim:

1. The process of preparing an ester of an acylated lactyllactic acid corresponding to the general formula wherein R and R are alkyl radicals containing from 5 to 17 and from 2 to 12 carbon atoms respectively, which comprises heating a molar excess of alkyl lactate having from 2 to 12 carbon atoms in the alkyl group with a saturated aliphatic monocarboxylic acid having from 6 to 18 carbon atoms, and concurrently removing the water formed in the reaction by distillation the heating being at a temperature of at least about 100 C. and in the presence of an acidic esteriflcation catalyst and an organic solvent water entraining agent, the heating being for several hours, to form a distillation residue containing said ester.

2. The process of preparing butyl lactyllactate laurate having the formula which comprises heating at reaction temperature a molar excess of'butyllactate with lauric acid and continuously removing the water formed in the reaction by distillation.

3. The process of claim 2 wherein the lauric acid is heated with at least two molecular proportions of butyl lactate in the presence of an acidic esterification catalyst, and the water is removed from the reaction mixture by azeotropic distillation with an entraining agent.

4. The process of claim 3 wherein the acidic esterification catalyst is p-toluene sulfonic acid and the entraining agent is toluene.

5. The process which comprises forming a mixture of butyl lactate, lauric acid, butyl laurate and butyl lactyllactate in approximate proportions of 0.5 mole of lauric acid, 1 mole butyl laurate and 0.3 mole butyl lactyllactate per mole of butyl lactate, heating the mixture at a temperature within the range of about -210 C., to remove the water formed in the reaction by distillation, thereafter subjecting the reaction mixture to distillation under reduced pressure to recover butyl esters of lactic, lauric and lactyllactic acids in the distillate and to produce a distillation residue consisting essentially of a mixture of butyl lactate laurate and butyl lactyllactate laurate in the molecular proportions of approximately 2 to 1.

6. A compound corresponding to the general formula 7. A composition of matter comprising butyl lactyllactate laurate having the formula:

8. A composition of matter comprising a mixture of butyl lactate laurate and butyl lactyllactate laurate in the molecular proportions of approximately two to one.

9. A composition of matter having an index of refraction n4 1.4403i0.0005 and consisting essentially of a mixture of butyl lactate laurate and butyl lactyllactate laurate.

10. The process of claim 1 in which at least two molecular proportions of alkyl lactate are present in the reaction, and with addition of the corresponding alkyl ester of said saturated aliphatic monocarboxylic acid to the reaction mixture.

11. A process of preparing butyl lactyllactate laurate comprising heating at reaction temperature a molar excess of butyl lactate with lauric acid, adding to the reaction mixture butyl laurate and butyl lactyllactate which had been recovered as by-product from reaction of butyl lactate with lauric acid, and continuously removing the water formed in the reaction by distillation.

CHARLES H. FISHER. MARTIN L. FEIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,927,295 Powers Sept. 19,. 1933 OTHER REFERENCES Fein et al., Ind. and Eng. Chem., March 1944, pages 235-238.

Filachione et al., Ind. and Eng. Ghent, May 1944, pages 472-475. 

1. THE PROCESS OF PREPARING AN ESTER OF AN ACYLATED LACTYLLACTIC ACID CORRESPONDING TO THE GENERAL FORMULA 